This invention relates to surface covers for reservoirs of liquid in which the cover material is a flexible impermeable synthetic rubber such as Hypalon; a registered trademark of the Dupont Company.
There are but two primary patents in this field. The first was granted to Dial, U.S. Re Pat. No: 30,146, Nov. 13, 1979, and the second was granted to Burke, et al, U.S. Pat. No. 3,991,900, Nov. 16, 1976.
Dial, discloses a method of removing rain water from reservoir covers by raising a central portion of the cover by the use of floats and collecting the water in an undefined, non-tensioned peripheral depending collection sump. Since, it is too expensive to place floats beneath the entire central portion, the floats are arranged in rows and in theory the rain water flows toward the peripheral sumps along channels between the rows of floats. In practice, however, the rainwater collects in random puddles throughout the central portion where it frequently collects in large quantities causing stress in the material leading to early failure of the cover or in cold climates, freezing and subjecting the cover to cutting as well as excess weights stress the central floating portion is untensioned.
Further, the collection sump is formed at an undefined site anywhere between the central floating area and the edge of the reservoir.
Burke, taught a reservoir cover structure for creating positionally defined sumps. The first primary method of creating the sump was to attach weights to the cover along intersecting lines. The second primary method was to attach lines of floats along intersecting lines. Burke, supra did not teach a cover having a defined peripheral sump formed by the combination of weights and floats.